FreeCalypso > hg > gsm-codec-lib
view WIP:gsmhr @ 604:54f0f1b74c25
libgsmhr1 TFO: require BFI=0 and SID=0 for homing
In order for a received frame to be recognized as DHF, we need
not only the correct bit pattern, but also BFI=0 and SID=0.
The BFI=0 requirement should be obvious, while the SID=0 requirement
is needed only for HR codec. With FR and EFR, SID classification
comes from the payload bits and no separate check is needed -
but in HR we get an out-of-band SID ternary flag. When SID=1,
no payload bits are used at all; when SID=2, we use only the first
33 bits of the payload. Therefore, it is proper to conditionalize
DHF acceptance on SID=0.
We already implemented this logic in the just finished full decoder;
now bring TFO code into agreement.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Thu, 04 Dec 2025 19:40:35 +0000 |
| parents | b7ddcb178ef6 |
| children |
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The present state of gsm-codec-lib Hg repository is a Work In Progress with respect to addition of libgsmhr1, a WIP library seeking to implement GSM-HR codec in a way that fits into the grander vision of Themyscira Wireless. In the present WIP state absolutely NO commitments are being made with regard to API stability - the current WIP API can change at any moment! As a reminder, NO binary packages or build recipes should be made from this WIP state! If you don't need GSM-HR codec, please use the latest stable release tarball; if you do need GSM-HR codec, please wait until libgsmhr1 reaches version 1.0.0 per SemVer. If you need some GSM-HR functions (e.g., frame packing and unpacking) and cannot wait for libgsmhr1 version 1.0.0, the acceptable interim solution is to lift those individual C modules out of this repository and plop them directly into your own code - doing so would be more acceptable than making installable packages out of the present WIP.